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β-Galactosidases are key enzymes in the food industry. Apart from the hydrolysis of the saccharide bond of lactose, they also catalyze transgalactosylation reactions, producing galactooligosaccharides (GOS) with prebiotic activity. Here we report the heterologous production in Pichia pastoris of a novel β-galactosidase from the fungus Thermothielavioides terrestris. The enzyme (TtbGal1) was purified and characterized, showing optimal activity at 60 °C and pH 4. TtbGal1 is thermostable, retaining almost full activity for 24 h at 50 °C. It was applied to the production of GOS from defined lactose solutions and acid whey, a liquid waste from the Greek yoghurt industry, reaching yields of 19.4 % and 14.8 %, respectively. HILIC-ESI-QTOF-MS analysis revealed the production of GOS with up to 4 saccharide monomers. The results demonstrate efficient GOS production catalyzed by TtbGal1, valorizing acid whey, a waste with a heavy polluting load from the dairy industry.

The hydrodeoxygenation of pure phenol in hexane solution and of catalytic biomass fast pyrolysis oil (bio-oil) over 10 %Ni/ZrO2 and 10 %Ni/WO3-ZrO2 catalysts was investigated in the present study, at relatively mild conditions (ca. 50−250 °C, 30 bar H2) in a continuous flow high-pressure fixed bed reactor. The catalysts were characterized for their structural, porosity, redox and acidic/basic properties which were used to rationalize the observed catalytic performance. The 10 %Ni/ZrO2 catalyst was very active and selective towards cyclohexanol in the phenol HDO experiments (100 % conversion and selectivity at 110 °C) but the enhanced acidity offered by the addition WO3 in ZrO2 was necessary to succeed a complete hydrodeoxygenation of phenol to cyclohexane at the low temperature of 150 °C with the 10 %Ni/WO3-ZrO2 catalyst. This catalyst was also proven very active in the hydrodeoxygenation of the catalytic bio-oil which consisted of mono-aromatics (i.e. alkyl-benzenes) and PAHs (mainly naphthalenes and indenes), and fewer oxygenated compounds (i.e. alkyl-phenols and benzofurans), providing a product oil containing mainly alkyl-cycloalkanes and fewer alkyl-benzenes, at the mild conditions of 210 °C and 30 bar H2.

Thermophilic enzyme systems are of major importance nowadays in all industrial processes due to their great performance at elevated temperatures. In the present review, an overview of the current knowledge on the properties of thermophilic and thermotolerant carbohydrate esterases and oxidative enzymes with great thermostability is provided, with respect to their potential use in biotechnological applications. A special focus is given to the lytic polysaccharide monooxygenases that are able to oxidatively cleave lignocellulose through the use of oxygen or hydrogen peroxide as co-substrate and a reducing agent as electron donor. Structural characteristics of the enzymes, including active site conformation and surface properties are discussed and correlated with their substrate specificity and thermostability properties.

Laccase-like multicopper oxidases (LMCOs) are a heterogeneous group of oxidases, acting mainly on phenolic compounds and which are widespread among many microorganisms, including Basidiomycetes and Ascomycetes. Here, we report the cloning, heterologous expression, purification and characterization of a novel LMCO from the thermophilic fungus Thermothelomyces thermophila. The 1953 bp lmco gene sequence comprises of 3 exons interrupted by 2 introns and according to the LccED database the translated sequence belongs to superfamily 6 of multicopper oxidases. After removal of the introns, the gene was transformed into Pichia pastoris, under the control of the alcohol oxidase (AOX1) promoter. The heterologous enzyme was purified with an apparent molecular weight of 80 kDa. TtLMCO1 displayed optimum activity at pH 4 and 50 °C and appeared thermostable up to 50 °C. A variety of phenolic compounds were oxidized by TtLMCO1, including standard laccase substrates such as ABTS and 2,6 dimethoxyphenol. The UV/Vis spectrum of purified TtLMCO1 indicates that it belongs to yellow laccase-like oxidases. The enzyme was used for the bioconversion of 2′,3,4-trihydroxychalcone to 3′,4′-dihydroxy-aurone, a bioactive aurone recently shown to possess inhibitory activity against several isoforms of the histone deacetylase complex (HDAC). Overall, the thermophilic yellow LMCO TtLMCO1 presents a number of superior properties with potential use in industrial biocatalysis.

The Perfectly Matched Layer (PML) method is a powerful approach to absorb outgoing waves from a finite computational domain in various media, such as elastic, poroelastic, anisotropic, and viscoelastic, by means of layers of artificial material placed at the finite domain boundaries. However, its use in most finite-element method (FEM) codes, which take into account viscous damping by employing only the Rayleigh and Lindsday damping formulation, is inadequate. This paper introduces a viscoelastic Perfectly Matched Layer (PML) formulation with Rayleigh-type damping for finite-element time-domain analyses. The PML formulations in the frequency- and time-domain are derived using a two-parameter complex coordinate stretching function. The displacement field is the only unknown variable in the formulation, so that the approach can be readily implemented in general finite-element codes. The weak form formulation in the time-domain is implemented in ABAQUS/Standard by merging it with a user-defined element (UEL) subroutine in Fortran90. The UEL is developed for 2D plane-strain (PE4ML) and plane-stress (PS4ML) four-node, linear, isoparametric, quadrilateral elements. The Hilber-Hughes-Taylor implicit time integration scheme is used to evaluate the unknown displacements, velocities, and accelerations. The validity and efficiency of the viscoelastic PML formulation and the UEL subroutine are examined with two numerical examples, namely a single-layer and a multi-layered soil profile with different damping ratios and properties. The results also highlight the poor performance of elastic PML layers, when they are placed at the boundaries of a viscoelastic interior domain, because, as the damping ratio increases, the reflection at the interface of the interior domain and the elastic PML domain increases. Long-time stability of the model is also examined, and no instabilities are observed.

Currently, there is no research effort on the efficient selection of earthquake records for the non-uniform excitation of bridges. The present investigation addresses this topic. Initially, the physics of the bridge response to asynchronous seismic excitations are illustrated. Next, two basic criteria are presented to provide insight into the selection of reference ground motions for the simulation of asynchronous excitations. The first criterion is the ratio of the zero-crossings of the reference ground displacement time series (n) to the total duration of the ground shaking (t), which can be evaluated by visual inspection of the displacement time series, and the second is the peak ground displacement. The former criterion is an indicator of the degree of sensitivity of the simulated displacement time series at various separation distances to the loss of coherency, and the numerical results of the present study indicate that the simulated waveforms of earthquake displacements with n/t greater than unity are highly dependent on coherency, i.e. become significantly modified by coherency, and, consequently, are more crucial for the pseudo-static response of bridges subjected to asynchronous seismic excitations. The latter criterion is also directly related to the magnitude of the pseudo-static force induced in the bridge structure. Finally, a brief discussion on the selection strategy of earthquake records for the seismic assessment of bridges is provided.

Deconvolution is the process that evaluates the seismic motion at depth of a soil profile, which can then be used as input excitation in soil-structure interaction (SSI) analyses. Clearly, the reliability of the SSI analysis depends on the precision of the derived deconvolved motions at depth. In this paper, the phase-amplitude modification procedure is presented to deconvolve both horizontal and vertical target (design) surface ground motions in multi-layered, equivalent-linear viscoelastic media for use in finite element time-domain structural analyses. The aim is to determine the seismic motions at the appropriate depth in the soil profile by modifying the target surface ground motions based on the mathematical model of the system, which is assessed by analyzing input-output data. The nonlinear behavior of the soil layers is approximated by employing the equivalent soil properties in the finite element model. The exact solution of vertical wave propagation, obtained with the SHAKE software, is used as a guide to obtain the equivalent properties of the soil layers, and evaluate the damping ratios. The procedure is validated using a multi-layered soil profile. The numerical results demonstrate that the convolved surface ground motions from the finite element analysis and the target ones are in almost perfect agreement, indicating that the approach can be used for reliable SSI evaluation in finite element time-domain analyses. Furthermore, the results indicate that the use of the deconvolved base motions resulting from SHAKE and applied directly in the finite element time-domain analysis may result in considerable error. In addition, the examination of different models of Rayleigh damping suggested that the optimized Rayleigh damping can decrease the frequency-dependency of the damping at high frequencies, which is more compatible with the frequency-independent behavior of soils, as verified experimentally by several researchers.

V2O5/TiO2 photocatalysts, with V2O5 particles supported on TiO2 (TV), N-TiO2 (NTV) and N/F-TiO2 (NFTV), were prepared with 5% wt. V2O5 loading and 450, 550 °C as calcination temperatures. XRD analysis showed the formation of anatase TiO2 and very small peaks of V2O5. DRS UV–vis spectra showed that V2O5 coupling extended the absorption edge into the visible light region. Photocatalysts calcined at 450 °C exhibited higher rates of Cr(VI) reduction and OH radical photogeneration than photocatalysts calcined at 550 °C. For catalysts at 450 °C, photocatalytic reduction of Cr(VI) follows the trend ΤV450 > ΝΤV450 > ΝFTV450 while the OH generation followed the reverse trend.

In order to model any physical system, including concrete dams, one needs to apply simplifications to the real system to make the modeling feasible. To study the dynamic response of concrete dams, relevant assumptions are made regarding foundation modeling, input motion mechanism, dam-reservoir interaction, and material behavior. Some of these simplifications may lead to more conservative and uneconomical outcomes. In this paper, nonlinear time-domain dynamic analyses are conducted to evaluate the effect of the input motion mechanism on the concrete gravity dam response. An ideal model of a dam-reservoir-foundation system, considering the inertia of the foundation, appropriate boundary conditions and precise deconvolved base motions, is selected as the reference model. The process of deconvolution of seismic waves through the frequency- and time-domain approaches is discussed, and suggestions for the selection of an appropriate damping model for the rock foundation are presented. The results are compared to those of the standard model of a massless foundation system as recommended by the US Army Corps of Engineers. The numerical results indicate that, generally, the nonlinear response of the two dam models follow similar patterns, but with a larger amplitude for the massless system. It is noted that the consequence of neglecting the dynamic effect of the foundation can be significant. Additionally, the results demonstrate that the degree of overestimation varies dramatically for the various seismic excitations. The average overestimation of the massless system for the crest displacement, crest acceleration, and the contact opening and sliding are 57%, 45%, 152%, and 90%, respectively. It is further shown that the use of the deconvolved input excitation at the base of the finite foundation derived from the frequency-domain approach can yield discrepancies between the target and convolved surface ground motions, which can also have a considerable effect on the dam response.

The field of enzymatic degradation of lignocellulose is actively growing and the recent updates of the last few years indicate that there is still much to learn. The growing number of protein sequences with unknown function in microbial genomes indicates that there is still much to learn on the mechanisms of lignocellulose degradation. In this review, a summary of the progress in the field is presented, including recent discoveries on the nature of the structural polysaccharides, new technologies for the discovery and functional annotation of gene sequences including omics technologies, and the novel lignocellulose-acting enzymes described. Novel enzymatic activities and enzyme families as well as accessory enzymes and their synergistic relationships regarding biomass breakdown are described. Moreover, it is shown that all the valuable knowledge of the enzymatic decomposition of plant biomass polymers can be employed towards the decomposition and upgrading of synthetic polymers, such as plastics.

The enzyme MtPerII is a new peroxidase which has been isolated only recently from fungus Myceliophthora thermophila and has significant thermostability and stability at high H2O2 concentrations. In the present work, an electrochemical kinetic study, based on cyclic voltammetry, is performed for the first time for the catalytic decomposition of H2O2 by MtPerII, at 18°C. Leuco methylene blue (LMB) is used as a mediator and the catalytic and Michaelis constants are determined, assuming a Michaelis-Menten mechanism. Experimental evidence suggest the absence of inhibition by H2O2, for concentrations up to 16mM, and increasing catalytic activity for temperatures up to 50°C. Moreover, a modified electrode is constructed, by attempting the entrapment of MtPerII on a dodecanothiol self-assembled monolayer on gold. The modified electrode is studied chronoamperometrically in solutions containing methylene blue mediator and different concentrations of H2O2. It is shown that adsorbed MtPerII retains its activity and the modified electrode exhibits a considerably high linear region for the detection of H2O2. The experimental findings indicate that MtPerII is a new candidate for analytical and industrial applications.

A membrane bioreactor (MBR), accomplishing high nitrogen removal efficiencies, was evaluated under various landfill leachate concentrations (50, 75 and 100% v/v). Proteinous and carbohydrate extracellular polymeric substances (EPS) and soluble microbial product (SMP) were strongly correlated (p

Dark tourism has recently garnered significant interest as a niche market on an academic level, witnessed by the increasing number of papers on the subject. Despite various attempts having been made to categorize different types of dark site, most of these have been place-dependent, therefore overshadowing the role of the cultural intermediary at a dark site. This conceptual research attempts to offer a different categorization of dark attractions based on the Netflix documentary series Dark Tourist. The aim is to show that, given the role played by the cultural intermediary in dark storytelling, some dark attractions are basically person-dependent and award little importance to the place, which opens up new marketing options within the dark attraction spectrum. Six fundamental roles of dark intermediaries are identified, ranging from typical tour guides to the villains themselves; that is, from light to darker person-dependent attractions.

This paper examines the role of the numerical modeling of soil-foundation-structure (SFS) interaction on the seismic response of a tall, partially embedded, flared bridge pier. For this purpose, static, pushover, nonlinear, finite-element, stand-alone analyses are performed on nine different models of one of the two piers of the Mogollon Rim Viaduct, a long-span, reinforced-concrete bridge supported on pile foundations. Structural modeling considerations, such as selection of concrete constitutive models, material properties, and bond-slip and P-Δ effects, on the nonlinear response of this pier are investigated. p-y, t-z and Q-z nonlinear curves are applied to model the soil-pile interaction, and equivalent nonlinear springs are developed to reproduce the soil-pile cap interaction. In addition, the effects of the partial pier embedment and the slope of the ground surface on the lateral resistance of the pier and the total capacity of the SFS system are examined. The results illustrate how structural and geotechnical modeling approaches for the SFS interaction can affect the nonlinear response of tall bridges, and may lead to differences in the numerical prediction of local or global failure. For the case analyzed herein, the partial pier embedment and foundation flexibility can dramatically modify the structural response, and influence the bond-slip effect at the pier-pile cap connection.

This study proposes a procedure for the estimation of the mean absolute input energy of multiple-support structures subjected to partially correlated, non-stationary, multi-component, seismic actions. The methodology extends the current evaluation of the earthquake input energy of single-support structures to multiple-support ones, and considers the combined action of translational and rotational components. A mean total velocity response spectrum for characterizing the mean absolute input energy of multiple-support structures is derived utilizing their pseudo-static response. The earthquake rotational loading is simulated considering the effects of both time delay and loss of coherency. The main advantage of the proposed method is its simplicity of application to a wide range of bridge systems. In addition, the effects of the geometrical configuration of the structure and the earthquake characteristics on the absolute input energy of straight short-span bridges along their longitudinal direction are parametrically investigated, and recommendations for their safe seismic design are proposed. The numerical results of this study indicate that, if the effect of the spatial variation of strong ground motions is incorporated in seismic analysis of bridges, both the differential and the rotational components of the strong ground motions should be taken into account in their excitation.

An unconventional urban environment often acts as an attraction for tourists. This is exemplified by the old city centre of Amsterdam, through its urban gentrification which offers a unique tourist experience through an interplay of contradicting concepts: legal and illegal, or moral and immoral. Based on Foucault's heterotopias of informational deviance and the informational role of tour guides, the aim of this paper is to show the critical influence of the tour guide's contribution to the tourist experience of visiting these often morally contradicting concepts. Tour guides operate in this context as ‘information filters’, based on the tourist guides' personalities and background. To analyse this information sensitivity, five tours were examined in the Red Light District, three related to prostitution and two to Coffee Shops. Through systematic participant observation, descriptive results were obtained, which highlight the importance of the guides' personal profile in interpreting this experience to tourists.

In the present work, a kinetic analysis is made concerning the reaction of an electroactive immobilized enzyme with a free substrate, based on a Michaelis-Menten scheme. The proposed kinetic equations are investigated numerically for conditions describing large amplitude fast Fourier transform alternating current voltammetry (FTacV), under different reaction states (transient or steady state for the reaction intermediate as well as quasi or complete reversibility of the electrochemical step). The dependence of two chief observables that occur from the analysis of the results of the method, that is, the maximum of the harmonics and the potential shift of the corresponding dominant peaks, on substrate concentration is presented. The FTacV method is applied experimentally for an immobilized laccase-like multicopper oxidase from Thermothelomyces thermophila, TtLMCO1, and its reaction with epinephrine. From the experimental findings it is shown that the intrinsic characteristics of the system do not lead to the extraction of the desired kinetic data although indications on the relation between the kinetic constants is revealed. Finally, the response of the third harmonic for the first additions of epinephrine at subnanomolarity range can be exploited for the detection of epinephrine at rather low concentrations.

The numerical modeling of the unbounded domain is one of the most challenging issues both for site response and soil-structure interaction analyses. The viscous-type absorbing boundary conditions (ABCs) are commonly used for the modeling of the unbounded domain due to their low computational cost and simplicity. However, in cases, their application can lead to substantial errors. In this paper, a time-domain viscoelastic perfectly matched layer (PML) is implemented for modeling the unbounded domain in the dynamic response evaluation of a concrete gravity dam. The performance of the viscoelastic PML and the viscous ABCs are examined through numerical examples under different types of dynamic excitations including uniform and spatially variable seismic ground motions. The numerical results highlight the excellent performance of the PML approach to model the unbounded domain under all types of excitations. It is also shown that the viscous-type ABCs perform poorly under spatially variable excitations and reflected waves from the structures, as they cannot properly absorb inclined waves. The nonlinear response of a concrete gravity dam subjected to deconvolved seismic excitations at depth resulting from five surface seismic records was then evaluated. The effect of the finite foundation depth on the dam response was also examined by considering a shallow (approximately equal to the height of the dam) and a deep (approximately double the height of the dam) finite foundation length. The results indicate that the PML is capable of maintaining its accuracy even if the size of the computational finite domain is reduced. On the other hand, it was shown that the shallow finite foundations modeled with viscous ABCs substantially underestimate the dam response under uniform excitations, whereas the use of a deep finite foundation model with viscous ABCs can lead to more conservative results. An important conclusion of this study is that the use of foundation models with viscous-type ABCs for the dynamic analysis of dams, and, consequently, other long structures, subjected to spatially variable excitations, should be avoided as it can significantly underestimate the crest displacement and the total damage in the dam.

We investigate the binding mechanism in renin complexes, involving three drugs (remikiren, zankiren and enalkiren) and one lead compound, which was selected after screening the ZINC database. For this purpose, we used ab initio methods (the effective fragment potential, the variational perturbation theory, the energy decomposition analysis, the atoms-in-molecules), docking, molecular dynamics, and the MM-PBSA method. A biological assay for the lead compound has been performed to validate the theoretical findings. Importantly, binding free energy calculations for the three drug complexes are within 3 kcal/mol of the experimental values, thus further justifying our computational protocol, which has been validated through previous studies on 11 drug-protein systems. The main elements of the discovered mechanism are: (i) minor changes are induced to renin upon drug binding, (ii) the three drugs form an extensive network of hydrogen bonds with renin, whilst the lead compound presented diminished interactions, (iii) ligand binding in all complexes is driven by favorable van der Waals interactions and the nonpolar contribution to solvation, while the lead compound is associated with diminished van der Waals interactions compared to the drug-bound forms of renin, and (iv) the environment (H2O/Na(+)) has a small effect on the renin-remikiren interaction.

Many studies have stated that tourists are searching for authenticity – or what they perceive as such – within foreign cultural contexts. Accepting forms of culture that reflect day-to-day life as tourist attractions, many tourists have developed an interest in the real life of their hosts. Yet, the definition of authenticity in tourism has become multifaceted. Divided between experiences and objects, authenticity has been perceived through either objective, constructive or postmodern approaches. This paper examines the various elements on which a new tourist attraction, namely Los Angeles Gang Tours, bases its commercialization upon authenticity as communicated through online communication channels. For this purpose, content analysis was applied to the textual and visual online data available. Finally, the discussion is developed as to what form of authenticity this tour represents, as well as the perception of authenticity that tourists share online after experiencing the tour.